JP4073140B2 - Thin film forming apparatus and thin film manufacturing method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
  The present invention relates to a thin film forming apparatus and a thin film manufacturing method for forming a thin film made of amorphous silicon or the like on a substrate using a chemical reaction by plasma.
[0002]
[Prior art]
  In recent years, a thin film forming apparatus using plasma CVD has been developed in which a plasma generating electrode disposed on a substrate has a substantially cylindrical shape and is rotated at a high speed (for example, special features). (See Kaihei 9-104985). An outline of the apparatus is shown in FIGS.
[0003]
  In FIG. 10, a substrate transfer table 12 is installed in a sealed chamber 10, and a substrate 14 is placed thereon, and the substrate transfer table 12 and the substrate 14 are connected to ground. A rotating electrode RE is disposed so as to face the substrate 14 with a slight gap. The rotating electrode RE has a rotating shaft 16 extending through the center of a substantially cylindrical electrode main body 18 extending in the depth direction in the drawing, and both ends of the rotating shaft 16 are rotatably supported by columns not shown. . The end of the rotating shaft 16 is connected to a high-frequency power supply (not shown) via a resonator 19 provided on the outer surface of the chamber.
[0004]
  In this apparatus, the inside of the chamber 10 is evacuated, and while rotating the rotating electrode RE, high-frequency power (or DC power) is applied to the rotating electrode RE to generate plasma 22 between the rotating electrode RE and the substrate 14, A reaction gas (SiH in the illustrated example) is supplied from a reaction gas supply source (not shown).₄And H₂Gas) and a dilution gas (for example, He) are introduced into the chamber 10, and these gases are caught between the rotating electrode RE and the substrate 14 by the rotation of the rotating electrode RE and guided to the plasma 22. Here, the reaction gas causes a chemical reaction. As a result of scanning the substrate 14 in a predetermined direction (direction orthogonal to the rotation axis direction of the rotating electrode RE) together with the substrate carrier 12 while causing such a chemical reaction, as shown in FIG. 11, a thin film ( In this example, a thin film made of amorphous silicon) 23 is formed.
[0005]
  This apparatus makes it possible to continuously form a uniform thin film 23 in a large area at a high speed and to generate glow discharge plasma under a pressure of 1 atm or more, which has been difficult in the past. It is an epoch-making means. However, when film formation is performed under high pressure and at high speed in this way, silicon that has not contributed to the film formation 23 as shown in FIG. 11 due to the rapid reaction gas decomposition reaction occurring in the gas phase. The atoms are connected to each other to form particles (fine particles) 24. When such particles 24 are deposited on the substrate 14, the surface form of the film 23 is disturbed and becomes a factor that hinders the formation of a high quality film.
[0006]
  Therefore, the publication discloses a duct 90 as shown in FIGS. 12 (a) and 12 (b) arranged downstream of the electrode rotation direction, and the particles 24 are sucked and removed through this duct 90. Yes. The duct 90 has a suction port 92 at the tip thereof formed in a tapered shape that is narrower than other portions, and the suction port 92 is located downstream of the rotation electrode RE in the rotation direction of the rotation electrode RE and the substrate 14. It is inserted in the gap with the top surface. The gas suction speed at the suction port 92 is equal to or higher than the peripheral speed of the electrode surface, preferably twice or more, more preferably 10 times or more the peripheral speed of the electrode surface.
[0007]
[Problems to be solved by the invention]
  FIG. 13 shows a gas flow state in the vicinity of the duct 90. As shown in this figure, the conventional apparatus using a duct has the following disadvantages.
[0008]
  A gap always exists between the upper surface of the duct 90 and the outer peripheral surface of the rotating electrode RE, or between the lower surface of the duct 90 and the upper surface of the substrate 14, so that gas is sucked into the duct suction port 92 through this gap. As a result, the gas suction speed in the vicinity of the rotating electrode RE decreases. Therefore, even if the suction port 92 is brought close to the rotary electrode RE and the suction speed at the suction port 92 is increased, there is a limit to increasing the gas suction speed in the vicinity of the electrode. Removal is difficult.
[0009]
  The particles are not necessarily small enough to be entrained in the air flow, but large particles that are scattered in the circumferential tangential direction of the rotating electrode RE due to inertial force (particle 24b shown in FIG. 13). Is also present. Further, the particles 24 are not necessarily transported from the gas phase to the downstream side (duct 90 side), but once separated from the surface of the rotating electrode RE, the particles 24 are separated and re-scattered. Sometimes. These particles cannot be collected effectively by the tapered duct 90.
[0010]
  Since the gas containing the particles 24 collides with the duct suction port 92 from the front, particles are likely to be deposited in the vicinity thereof (particles 24c shown in FIG. 13), and the duct itself in which such particles 24c are deposited becomes a contamination source. There is a fear.
[0011]
  The gas flow in the circumferential direction of the electrode dragged by the high-speed rotating electrode RE and the gas flow sucked from the gap between the rotating electrode RE and the duct 90 are mixed to generate a plasma 22 generation region. The vortex W is formed at a position not far away. This vortex W causes active reaction intermediates or clusters thereof to stay for a long time and is a factor for promoting particle growth.
[0012]
  A flow stagnation region 94 is formed in the vicinity of the substrate 14 due to the flow of gas sucked from the gap between the upper surface of the substrate 14 and the duct 90. This stagnation region 94, like the vortex W, causes active reaction intermediates or clusters thereof to stay for a long time, and is a factor that promotes particle growth.
[0013]
  Further, as a factor that hinders good thin film formation depending on film forming conditions such as raw material gas concentration and rotating electrode temperature, in addition to the generation of particles in the gas phase, the rotating electrode has the same mechanism as the thin film formation on the substrate 14. It is conceivable that a thin film formed on the outer peripheral surface of the RE grows and further peels off and adheres to the substrate surface. It is difficult to remove such a peeling component by the duct 90. This hindering factor can be avoided by periodically cleaning the rotating electrode RE by dry etching or the like. However, the cleaning requires considerable time and hinders improvement of operation efficiency.
[0014]
  In view of such circumstances, the present invention drastically solves the problem of thin film formation that has conventionally occurred by using the rotating electrode and enables high-speed formation of a high-quality film. An object is to provide a thin film forming apparatus and a thin film manufacturing method.
[0015]
[Means for Solving the Problems]
  In order to solve the above-mentioned problem, first, a detailed study will be made below regarding the mechanism of thin film formation inhibition that causes the problem.
[0016]
  1) Generation of particles in the gas phase
  It is considered that the following relationship exists between the state of the plasma generation region between the rotating electrode and the substrate and the thin film and particles in the region.
[0017]
  A sheath region having a steep electric field gradient exists in the vicinity of the rotating electrode and the substrate, and a bulk region having a relatively gentle electric field gradient exists between these sheath regions. The energy of electrons is increased mainly in the sheath region, and energy is lost by colliding with gas molecules at the boundary between the sheath region and the bulk region. Therefore, chemically active radical molecules, excited molecules and ions having high internal energy are localized near the boundary portion.
[0018]
  FIGS. 14A and 14B show the emission intensity distribution in the plasma generation region in a conventional thin film forming apparatus using a rotating electrode. This distribution shows the detection result of the intensity of light emitted when the excited molecules return to the ground state. Therefore, a high emission intensity distribution means that radical molecules and excited molecules are actively generated in that region.
[0019]
  Referring to FIGS. 14A and 14B, the emission intensity is locally high near the boundary between the sheath region / bulk region near the substrate and near the boundary between the sheath region / bulk region near the rotating electrode, Therefore, it can be understood that radical molecules and excited molecules are actively generated in these regions. Moreover, as is apparent from a comparison of FIGS. 4A and 4B, the emission intensity distribution becomes steeper as the operating pressure increases. This is presumably because the collision probability of electrons and molecules increases with increasing pressure, the generation rate of radical molecules and excited molecules increases, and the diffusion coefficient decreases.
[0020]
  Of these, radical molecules, excited molecules, and ions generated near the boundary between the sheath region / bulk region on the side close to the substrate are immediately formed on the substrate or become other reaction intermediates before the substrate. A film is formed on top. On the other hand, most of radical molecules, excited molecules, and ions generated near the sheath / bulk region boundary near the rotating electrode are not as high as the substrate temperature. Clustering and further micronization in the gas phase will generate particles. Therefore, by suppressing the generation of radical molecules, excited molecules, and ions in the vicinity of the latter rotating electrode, it is possible to realize good thin film formation while effectively suppressing particles.
[0021]
  2) About thin film formation on the peripheral surface of the rotating electrode
  As described above, in plasma CVD, a thin film is formed by the active species generated in the vicinity of the substrate in the plasma space adhering to the substrate surface. However, depending on the film formation conditions such as the source gas concentration and the rotating electrode temperature, In addition, a thin film is formed on the electrode surface by the same mechanism as in the vicinity of the substrate, and its thickness increases in proportion to the processing time. If this is left uncleaned, when the film grown on the electrode surface reaches a certain thickness, it peels off and becomes flakes, part of which adheres to the substrate surface, pinholes, etc. It will give a defect. Such a failure due to the formation of a thin film on the outer peripheral surface of the rotating electrode can be drastically solved by suppressing the formation of the thin film on the rotating electrode side itself.
[0022]
  The present invention has been made from such a viewpoint, and while holding a substrate at a position facing the rotating electrode, a rotating electrode having a cylindrical outer peripheral surface, driving means for rotating the rotating electrode, and the rotating electrode. A feeding means for moving the substrate relative to the rotating electrode in a direction substantially orthogonal to the rotation center axis, and generating plasma between the rotating electrode and the substrate while rotating the rotating electrode, In the thin film forming apparatus for forming a thin film on the substrate by causing a chemical reaction to the reactive gas supplied to the plasma, an area on the outer peripheral surface of the rotating electrode corresponding to at least the thin film forming area on the substrate And a purge gas layer forming means for forming a gas layer made of a purge gas different from the reaction gas.
[0023]
  In this apparatus, the purge gas layer forming means forms a very thin purge gas viscous bottom layer on the surface of the rotating electrode (specifically, it is thinner than the distance between the rotating electrode and the substrate and from the rotating electrode to the sheath region / bulk on the rotating electrode side). By forming a layer thicker than the distance to the region boundary portion, the purge gas concentration in the layer formation region (for example, when helium is used as the purge gas, the helium concentration or helium radical concentration) is increased. On the other hand, the concentration of the raw material gas (for example, silane gas) generated near the boundary between the sheath region and the bulk region near the rotating electrode and the concentration of radical species of the raw material gas can be suppressed. As a result, the generation of particles in the vicinity of the rotating electrode can be effectively suppressed, and the formation of a thin film on the outer peripheral surface of the rotating electrode can also be prevented. On the other hand, in the vicinity of the boundary between the sheath region and the bulk region close to the substrate, a good thin film can be formed on the substrate based on the source gas, as in the conventional apparatus (see FIG. 15).
[0024]
  Furthermore, in the present invention,As the purge gas layer forming means,On the outer peripheral surface of the rotating electrode, a gas ejection portion is provided at least in a region corresponding to the thin film formation region on the substrate, and a gas supply portion communicating with the gas ejection portion is provided at a position different from the gas ejection portion. Purge gas supply means is provided for supplying a purge gas different from the reaction gas to the supply unit and ejecting the purge gas from the gas ejection unit of the rotating electrode onto the electrode circumferential surface.It is.With this configuration, a uniform purge gas layer can be formed on the outer peripheral surface of the rotating electrode.
[0025]
  Furthermore, in the present invention,The rotating electrodeofThe electrode main body is formed into a hollow, substantially cylindrical shape, and a gas jet passage is provided on the peripheral wall of the electrode main body to communicate the inside and outside of the electrode main body, and a gas supply path that communicates the space inside the electrode main body with the gas jet section.It is said. ThisThe entire electrode can be reduced in weight, and the gas ejection portion and the gas supply path inside the electrode can be easily formed.
[0026]
  Furthermore, in the present invention,Gas supply part of rotating electrodeTheProvided on the electrode rotation center axising. According to this configuration, since the position of the gas supply unit does not move even while the rotating electrode is rotating at a high speed, the purge gas can be supplied to the rotating electrode more easily and stably.
[0027]
  SpecificallyIsIn the rotating electrode comprising the hollow electrode body as described above,A cylindrical rotation shaft passes through the central portion of the electrode body in the axial direction, the shaft end opening of the rotation center shaft serves as a gas supply portion, and a gas outlet portion communicates the inside and outside with the peripheral wall of the rotation center shaft The space between the rotation center axis and the electrode body is a gas stirring chamber.HaveThe According to this configuration, the purge gas supplied from the shaft end opening of the cylindrical rotating shaft enters the gas stirring chamber outside the rotating shaft through the gas outlet portion of the rotating shaft, and after being stirred here, The gas is ejected substantially uniformly from the gas ejection portion to the outside of the rotating electrode.
[0028]
  The rotary electrode has a simple structure in which a purge gas supply pipe is simply inserted into the shaft end opening of the rotation center shaft that is the gas supply section, and the purge gas supply means is inserted into the rotation center shaft through the purge gas supply pipe. Purge gas can be supplied, and this purge gas can be ejected from the gas ejection portion of the rotating electrode.
[0029]
  The purge gas may be any gas that does not affect the chemical reaction for forming the thin film. For example, when a thin film made of amorphous silicon or the like is formed on a substrate using a gas containing silane gas as the reaction gas, the purge gas is an inert gas such as helium (neon, argon, krypton, xenon, etc.) In addition, hydrogen, nitrogen, oxygen, or a mixed gas thereof can be applied.
[0030]
  As the gas ejection part, it is preferable to provide a gas ejection hole penetrating the electrode body at a plurality of positions aligned in the axial direction on the circumferential surface of the electrode body.
[0031]
  Furthermore, it is more preferable that the gas ejection holes are provided at a plurality of positions aligned in the circumferential direction on the circumferential surface of the electrode body. In this case, it is possible to equalize the ejection of the purge gas from the rotating electrode in the axial direction by shifting the axial positions of the gas ejection holes from each other.
[0032]
  Further, as the gas ejection part, it is also preferable that at least a part of the peripheral wall of the electrode body is made of a porous body extending in the axial direction of the electrode body. Also with this configuration, it becomes possible to supply the purge gas substantially uniformly in the axial direction from the porous body extending in the axial direction of the electrode body.
[0033]
  The purge gas layer further includes purge gas supply means for supplying purge gas from the upstream side in the rotation direction of the rotary electrode to the gap between the rotary electrode and the substrate or a position near the gap, and the supplied purge gas enters the gap. It can also be formed by a configuration in which a gas layer is formed by being involved.
[0034]
  Further, the present invention generates a plasma between the rotating electrode and the substrate while rotating the rotating electrode having a cylindrical outer peripheral surface, thereby causing a chemical reaction to occur in the reaction gas supplied to the plasma. A method of forming a thin film on a substrate, comprising: forming a gas layer made of a purge gas different from the reaction gas on an outer peripheral surface of the rotating electrode and corresponding to a thin film formation region on the substrate. It is provided.
[0035]
  In particular,On the outer peripheral surface of the rotating electrode, a gas ejection portion is provided at least in a region corresponding to the thin film formation region on the substrate, and a gas supply portion communicating with the gas ejection portion is provided at a position different from the gas ejection portion. Supplying the purge gas to a part and ejecting the purge gas from the gas ejection part of the rotating electrode onto the electrode peripheral surface.
[0036]
  further,In the method of the present invention, the electrode body of the rotating electrode is formed into a hollow, substantially cylindrical shape, a gas ejection portion that communicates the inside and the outside is provided on the peripheral wall of the electrode body, and the space inside the electrode body is defined as the gas ejection portion. Use a gas supply path.
[0037]
  On the other hand, the gas supply unit is installed on the central axis of the rotating electrode.Kick.
[0038]
  Specifically, the present inventionIn the method, a cylindrical rotation in the center of the electrode bodycenterA shaft is made to pass through, and the shaft end opening of the rotation center shaft is used as a gas supply portion, and a gas outlet portion is provided on the peripheral wall of the rotation center shaft so as to communicate between the inside and the outside, and between the rotation center shaft and the electrode body The space into a gas stirring chamberDo.
[0039]
  More specifically, it is preferable to insert a purge gas supply pipe into the shaft end opening of the rotation center shaft, which is a gas supply section of the rotating electrode, and supply the purge gas into the rotation center shaft through the purge gas supply pipe. .
[0040]
  As for the supply of purge gas, purge gas is supplied from the upstream side in the rotation direction of the rotary electrode to the gap between the rotary electrode and the substrate or in the vicinity thereof, and the gas layer is formed by entraining the supplied purge gas into the gap. It is preferable to do this.
[0041]
  Here, as the rotating electrode, it is more preferable to use a gas ejection hole provided with a gas ejection hole penetrating the electrode body at a plurality of positions aligned in the axial direction on the circumferential surface of the electrode body as the gas ejection part. It is more preferable if the gas ejection holes are provided at a plurality of positions arranged in the circumferential direction on the circumferential surface of the electrode body, and the rotary electrodes are configured such that the axial positions of the gas ejection holes are shifted from each other.
[0042]
  Further, the rotating electrode may be configured such that at least a part of a peripheral wall of the electrode main body is formed of a porous body extending in the axial direction of the electrode main body as the gas ejection portion.
[0043]
  The purge gas may be any gas that does not affect the chemical reaction for forming the thin film. For example, when a thin film made of amorphous silicon or the like is formed on a substrate using a gas containing silane gas as the reaction gas, the purge gas is an inert gas such as helium (neon, argon, krypton, xenon, etc.) In addition, hydrogen gas, nitrogen gas, oxygen gas, a mixed gas thereof, and the like are preferable.
[0044]
  The present invention can be applied to, for example, amorphous silicon, C, SiC, SiO₂It can use suitably for manufacture of the thin film which consists of etc.
[0045]
DETAILED DESCRIPTION OF THE INVENTION
  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. In addition, the thin film material formed in this invention is not restricted to the following amorphous silicon, For example, C, SiC, SiO₂It can be widely applied to materials that can form a thin film by a chemical reaction using plasma.
[0046]
  The thin film forming apparatus shown in FIGS. 1 to 3 includes a chamber 10 whose inside is sealed. A table 11 is installed at the bottom of the chamber 10. A substrate transport table 12 is provided on the table 11 and is slidably driven in a direction (left and right direction in FIG. 1) orthogonal to a rotation center axis of a later-described rotating electrode RE. The substrate carrier 12 is driven to slide while holding the substrate 14 in an exposed state. Accordingly, the substrate transport table 12 and the table 11 constitute a feeding means for scanning the substrate 14.
[0047]
  The rotating electrode RE is provided immediately above the substrate carrier 12. The height position is set such that a gap (for example, 0.1 mm to 1 mm) suitable for performing plasma CVD is maintained between the peripheral surface of the rotating electrode RE and the substrate 14.
[0048]
  The rotating electrode RE includes a hollow and substantially cylindrical electrode body 18 and a rotating shaft 16 that passes through the electrode body 18 in the axial direction. Both ends of the rotating shaft 16 are rotatably supported by a pair of bearing bases 13 provided in the chamber 10. One end of the rotating shaft 16 is connected to an output shaft of a motor (rotation driving means; see FIG. 2) 73 fixed to the chamber 10 via a coupling 74, and the operation of the motor 73 causes the entire rotating electrode RE to move at high speed. It is designed to rotate.
[0049]
  The rotary shaft 16 is connected to a high frequency power source 20 via an electrical connecting member 17 and a resonator 19 outside the chamber. A high-frequency voltage for film formation is applied from the high-frequency power source 20 to the rotating electrode 18 through the resonator 19 and the electrical connection member 17. It is also possible to use a direct current power source for this power source.
[0050]
  The structure of the rotating electrode RE is shown in FIGS.
[0051]
  The rotating shaft 16 of the rotating electrode RE has a cylindrical shape. That is, the rotating shaft 16 is provided with a through hole 16a penetrating in the axial direction. Further, the peripheral wall of the rotating shaft 16 is provided with a plurality of gas outlet holes 16b penetrating in the radial direction (that is, communicating with the inside and the outside of the rotating shaft) at appropriate positions.
[0052]
  The electrode body 18 includes a cylindrical peripheral wall 18r and circular side walls 18s that close the openings at both ends. The rotating shaft 16 is fixed to the side walls 18 s in a state of penetrating the side walls 18 s of the electrode body 18. The internal space of the electrode body 18, that is, the space sandwiched between the electrode body 18 and the rotating shaft 16 is a gas stirring chamber 18a.
[0053]
  Further, the peripheral wall 18r of the electrode body 18 is provided with a large number of small-diameter gas ejection holes 18b penetrating therethrough in the radial direction. In the illustrated example, these gas ejection holes 18b are arranged in the axial direction along eight rows arranged in the circumferential direction. Further, as shown in FIG. 5, by providing the gas ejection holes 18b in each row with their positions shifted in the axial direction, it becomes possible to equalize the ejection of the purge gas described later in the electrode axial direction.
[0054]
  However, in the present invention, the arrangement position and the number of the gas ejection holes 18b can be appropriately set. For example, in order to more effectively suppress the adhesion of the film to the surface of the rotating electrode, it is desirable to uniformly arrange the gas ejection holes 18b on the entire surface of the electrode peripheral wall 18r. It is also effective to arrange the partial ejection holes 18 as shown.
[0055]
  Further, the hole diameter may be set as appropriate in consideration of the relationship with the gas ejection pressure. Specifically, about 0.3 to 5 mm is preferable.
[0056]
  As shown in FIG. 6, the purge gas supply pipe 30 is inserted along the axial direction of the opening at one end of the rotating shaft 16 (the end opposite to the shaft connected to the motor 73). Yes. The outer diameter of the purge gas supply pipe 30 is set to be slightly smaller than the inner diameter of the rotary shaft 16, and only a small minute gap 32 is provided between the outer peripheral surface of the purge gas supply pipe 30 and the inner peripheral surface of the rotary shaft 16. Is secured. The purge gas supply pipe 30 itself penetrates the side wall of the chamber 10 and is fixed to the chamber side wall in a state where a seal is made at the penetration portion.
[0057]
  Next, a gas supply / discharge facility for the chamber 10 will be described with reference to FIG.
[0058]
  A gas circulation system 80 is connected to the chamber 10. In the gas circulation system 80, the gas in the chamber 10 is sucked into the dry pump 82 through the powder removal filter 81 from the exhaust port 10a. A part of the discharge gas of the dry pump 82 is released to the atmosphere through the silane removal device 83, and the rest is returned from the supply port 10 b into the chamber 10 through the water adsorption cylinder 84.
[0059]
  Further, a helium gas container 86, a hydrogen gas container 87, a methane gas container 88, and a silane gas container 89 are connected in the chamber 10, and the contained gas is appropriately supplied into the chamber 10 from these containers 86 to 89. It is like that. Further, the helium gas container 86 is connected to the purge gas supply pipe 30 separately from the direct connection to the chamber 10.
[0060]
  Next, the operation of this apparatus will be described.
[0061]
  Purge gas (helium gas in this embodiment) is sent from the helium gas container 86 through the purge gas supply pipe 30 into the rotary shaft 16 while the chamber 10 is evacuated and the rotating electrode RE is rotated by the operation of the motor 73.
[0062]
  The purge gas enters the gas stirring chamber 18a from the axial through hole 16a of the rotating shaft 16 through the gas outlet holes 16b in the radial direction, and further receives the centrifugal force due to the electrode rotation and receives the centrifugal force from the electrode rotation from the gas ejection holes 18b. Erupts outside. The ejected purge gas rotates in the same direction as being dragged by the outer peripheral surface of the rotating electrode RE that rotates at a high speed, and forms a thin purge gas layer around the outer peripheral surface of the electrode.
[0063]
  As described above, the purge gas layer is preferably thinner than the distance between the rotating electrode and the substrate, and thicker than the distance from the rotating electrode to the sheath region / bulk region boundary portion on the rotating electrode side. The layer thickness can be freely adjusted by the diameter and number of the gas ejection holes 18b, the supply pressure of the purge gas, and the like.
[0064]
  On the other hand, while applying high-frequency power (or DC power) to the rotating electrode RE to generate plasma between the rotating electrode RE and the substrate 14, a reactive gas (in this embodiment) SiH₄, H₂And CH₄) And a diluent gas (He in this embodiment) are introduced into the chamber 10, and these gases are engulfed between the rotating electrode RE and the substrate 14 by the high-speed rotation of the rotating electrode RE and are introduced into the plasma 22. It causes a chemical reaction. At the same time, the substrate 14 is scanned in the direction orthogonal to the rotation axis direction of the rotating electrode RE together with the substrate carrier 12, thereby forming a thin film (a thin film made of amorphous silicon in the illustrated example) on the substrate 14.
[0065]
  Here, conventionally, not only the vicinity of the substrate 14 but also the radical species of the silane gas generated in the vicinity of the rotating electrode RE cause a chemical reaction to generate particles (fine particles). Although the thin film formed on the RE may peel off and prevent the formation of a good thin film, the apparatus shown here forms a thin purge gas layer on the radially outer side of the rotating electrode RE. In other words, the layer functions as a barrier, and the generation of particles near the rotating electrode is effectively suppressed. In addition, the formation of the purge gas layer can effectively suppress the formation of a thin film on the rotating electrode RE, and can prevent the thin film from peeling off and adhering to the substrate surface side in advance. As a result, good thin film formation can be realized.
[0066]
  In this embodiment, the gas ejection hole 18b is provided in the rotating electrode peripheral wall 18r. Instead, a part of the peripheral wall 18r extends in the electrode axial direction as shown in FIGS. 7 (a) and 7 (b). It is configured by the porous body 18c, or as shown in FIGS. 8A and 8B, the entire peripheral wall 18r may be configured by the porous body 18c, and gas may be ejected from the porous body 18c. .
[0067]
  As this porous body 18c, for example, porous silicon nitride (Si₃N₄) And porous alumina (Al₂O₃) Is preferred. Moreover, application of a porous sintered metal is also possible.
[0068]
  In the illustrated example, the porous body 18c extends over the entire area of the electrode body 18 in the axial direction, and the purge gas can be ejected uniformly over the axial direction. The specific shape and number of the porous body 18c can be freely set.
[0069]
  In this way, whether the porous body 18c is used or the gas ejection hole 18b as described above is provided, the gas ejection area may be set to an area including at least a thin film formation area on the substrate.
[0070]
  The gas supply part of the rotating electrode RE can be provided on the side wall 18 s of the electrode body 18, for example. However, as described above, the rotating shaft 16 is cylindrical and the opening of the shaft end is used as the gas supply port. For example, even when the rotating electrode RE is rotating at high speed, the purge gas can be easily supplied to the inside thereof. The supply can be performed with a simple structure in which, for example, the purge gas supply pipe 30 is inserted into the shaft end opening of the rotary shaft 16 as shown in the figure.
[0071]
  Here, the insertion depth of the purge gas supply pipe 30 and the clearance with the rotary shaft 16 can be set as appropriate. The deeper the insertion depth and the smaller the clearance, the smaller the purge gas leakage and the better the purge gas supply efficiency.
[0072]
  The purge gas supplied to the rotating electrode RE is not limited as long as it has a property that does not inhibit the thin film formation reaction. In addition to the inert gas including the helium gas, hydrogen, nitrogen, oxygen, or a mixed gas thereof may be used. Also good. Further, the purge gas for the electrode may be the same type as the dilution gas supplied into the chamber 10 or a different type.
[0073]
  The temperature of the purge gas is not particularly limited, but is preferably higher than the atmospheric temperature in the chamber. By doing so, an appropriate purge gas layer thickness can be ensured while suppressing the amount of purge gas diffusing into the atmosphere by the centrifugal force of electrode rotation.
[0074]
  As described above, by adopting the means for providing the gas ejection portion in the rotating electrode RE, a uniform purge gas layer can be formed on the outer peripheral surface of the rotating electrode RE. However, the purge gas layer can be formed by other means as well. Is possible.
[0075]
  For example, as shown in FIG. 9, a purge gas supply pipe 32 penetrating the side wall of the chamber 10 is provided on the upstream side in the rotation direction of the rotary electrode RE, and a gas ejection end of the purge gas supply pipe 32 is connected to the rotary electrode RE and the substrate 14. The other end is connected to a purge gas supply source (for example, the helium gas container 86) so as to be directed to the gap or the vicinity thereof, and the purge gas is injected from the purge gas supply pipe 32 to the gap or the vicinity thereof. When the purge gas is caught in the gap by high-speed rotation of the rotating electrode RE, a region on the outer peripheral surface of the rotating electrode RE corresponding to at least a thin film forming region on the substrate 14 (region where the plasma 22 is formed). A purge gas layer 34 is formed. In this case, a plurality of the purge gas supply pipes 32 are arranged in the width direction of the rotary electrode RE, or the opening width of the ejection port of the purge gas supply pipe 32 is made substantially equal to the width of the rotary electrode RE. It is possible to make the gas layer uniform in the width direction. However, as shown in FIGS. 4 to 7, the purge gas layer can be made more uniform by providing the gas ejection portion on the peripheral surface of the rotating electrode RE.
[0076]
【Example】
  Amorphous silicon was selected as the thin film material, and the following film formation experiment was conducted.
[0077]
  1) Equipment conditions
  In the experiment, an apparatus including an aluminum alloy drum electrode (rotary electrode RE in FIG. 1), a high-speed rotation motor, a substrate transfer table (substrate transfer table 12 in FIG. 1), an impedance matching device, and the like was used. In order to prevent the vibration, the high speed motor was connected through a magnet coupling and a magnetic fluid seal. A high-frequency power source of 150 MHz was used, and high-frequency power was applied to the electrode part via the impedance matching unit to generate plasma in the narrowest gap part of 200 μm. The dimensions of the rotating electrode were 300 mm in diameter and 100 mm in width, and the maximum rotating speed was set to 5000 rpm (circumferential speed 79 m / s).
[0078]
  Further, as shown in FIGS. 4A, 4B and 5, the rotary electrode is provided with a large number of gas ejection holes (hole diameter: 0.5 mm) in the axial direction along eight rows arranged in the circumferential direction. The purge gas was ejected from the structure shown in FIG.
[0079]
  On the other hand, as the gas circulation system 80 shown in FIG.³A / min dry pump and a particle removal filter with a 0.1 μm mesh were connected to the chamber.
[0080]
  2) Implementation conditions
  The glass substrate that had been washed and dried was set on a sample stage, a film formation gap (narrowest gap δ) was set, and then evacuation was performed. Thereafter, helium (diluted gas) and a mixed gas of hydrogen and silane (reactive gas) are introduced into the chamber through a mass flow controller, and a small amount of helium gas is ejected as a purge gas to the surface of the rotating electrode. Atmospheric pressure. In this state, plasma was generated while rotating the electrode, and an amorphous silicon thin film was formed on the substrate. The film formation conditions were a hydrogen concentration of 0 to 10%, a silane concentration of 0.01 to 10%, an atmospheric pressure of 1 atmosphere, a substrate temperature of 250 ° C., and a film formation time of 30 seconds.
[0081]
  As a result, a uniform thin film can be obtained without generating particles in a wide range of input power of 300 to 2500 W and electrode rotation speed of 1000 to 5000 rpm, and the obtained thin film is exactly amorphous silicon. This was confirmed by Raman spectroscopy. After that, the experiment was continued for 5 batches, but no particle deposition or thin film formation was observed on the inner wall of the chamber or the surface of the rotating electrode.
[0082]
  Furthermore, when the weight increment of the particle removal filter before and after the experiment of 50 batches, that is, the collected particle weight was measured, it was found that the collected amount was 1/10 of that of the conventional apparatus. This result clearly shows that the implementation of the present invention effectively suppresses the generation of particles and improves the ratio of the source gas that contributes to the film formation on the substrate.
[0083]
  Further, as a modification, when a silicon rubber heater is wound around the purge gas supply pipe to purge the purge gas, it is possible to prevent adhesion of particles to each part of the reaction chamber and formation of a thin film on the rotating electrode while further reducing the supply amount of the purge gas. found.
[0084]
【The invention's effect】
  As described above, in the present invention, a gas layer made of a purge gas not involved in the thin film formation reaction is formed on the outer peripheral surface of the thin film forming rotating electrode. By effectively suppressing the contamination of the substrate surface due to, and suppressing the film formation on the rotating electrode, there is an effect that a high quality film can be formed at a high speed.
[Brief description of the drawings]
FIG. 1 is a cross-sectional front view of a thin film forming apparatus according to an embodiment of the present invention.
FIG. 2 is a sectional side view of the thin film forming apparatus.
FIG. 3 is a piping diagram showing a gas supply / discharge facility of the thin film forming apparatus.
4A is a perspective view of a rotating electrode used in the thin film forming apparatus and provided with gas ejection holes, and FIG. 4B is a sectional front view thereof.
FIG. 5 is a development view of the electrode body showing the arrangement positions of the gas ejection holes.
FIG. 6 is a cross-sectional side view showing a gas supply structure to the inside of the rotating electrode.
7A is an example of a rotating electrode used in the thin film forming apparatus, and is a perspective view of the rotating electrode in which a porous body for gas ejection is provided in a part of the circumferential direction, and FIG. It is a cross-sectional front view.
8A is an example of a rotating electrode used in the thin film forming apparatus, and is a perspective view of the rotating electrode in which a porous body for gas ejection is provided in the entire circumferential direction, and FIG. 8B is a cross-sectional view thereof. It is a front view.
FIG. 9 is a cross-sectional front view showing another embodiment of the present invention.
FIG. 10 is a schematic configuration diagram showing a conventional thin film forming apparatus.
11 is a view showing a mechanism for forming a thin film between a rotating electrode and a substrate in the thin film forming apparatus shown in FIG.
12A is a cross-sectional front view showing the arrangement of ducts in a conventional thin film forming apparatus, and FIG. 12B is a perspective view of the ducts.
13 is a cross-sectional view showing a gas flow in the thin film forming apparatus shown in FIG.
FIGS. 14A and 14B are diagrams showing emission intensity distributions in a plasma generation region in a conventional thin film forming apparatus.
FIG. 15 is an explanatory diagram showing a particle generation inhibiting mechanism according to the present invention.
[Explanation of symbols]
  10 chambers
  12 Substrate transfer table
  14 Substrate
  16 Rotating shaft
  16a Through hole
  16b Gas outlet hole
  18 Electrode body
  18a Gas stirring chamber
  18b Gas outlet
  18c porous material
  18r electrode body peripheral wall
  30, 32 Purge gas supply pipe
  86 Helium gas container (purge gas supply means)
  RE Rotating electrode

Claims (18)

A rotating electrode having a cylindrical outer peripheral surface, driving means for driving the rotating electrode to rotate, and holding the substrate at a position facing the rotating electrode, the substrate is substantially orthogonal to the rotation center axis with respect to the rotating electrode. And a feed means for moving in the direction of rotation, and generating a plasma between the rotating electrode and the substrate while rotating the rotating electrode, thereby causing a chemical reaction to occur in the reaction gas supplied to the plasma. In a thin film forming apparatus for forming a thin film on the substrate,
A purge gas layer forming means for forming a gas layer made of a purge gas different from the reaction gas on an outer peripheral surface of the rotating electrode and at least in a region corresponding to a thin film forming region on the substrate;
The purge gas forming means is provided on the outer peripheral surface of the rotating electrode at least in a region corresponding to the thin film forming region on the substrate, and is provided at a position different from the gas jetting portion and communicates with the gas jetting portion. And a purge gas supply means for supplying the purge gas to the gas supply unit and ejecting the purge gas from the gas ejection part of the rotating electrode onto the electrode circumferential surface,
The electrode body of the rotating electrode has a hollow, substantially cylindrical shape, and a gas ejection portion that communicates the inside and outside of the electrode body is provided on the peripheral wall of the electrode body, and a gas supply path that communicates the space inside the electrode body with the gas ejection portion,
A cylindrical rotation center shaft is passed through the central portion of the electrode body, a shaft end opening of the rotation center shaft is used as a gas supply portion, and a gas outlet portion is provided on the peripheral wall of the rotation center shaft to communicate the inside and outside. A thin film forming apparatus characterized in that a space between the rotation center axis and the electrode body is a gas stirring chamber. 2. The thin film forming apparatus according to claim 1 , further comprising a purge gas supply pipe inserted into an opening of a shaft end of a rotation center shaft that is a gas supply portion of the rotation electrode, and supplying the purge gas into the rotation center shaft through the purge gas supply tube. A thin film forming apparatus characterized by comprising a purge gas supply means. 3. The thin film forming apparatus according to claim 1 , wherein the reaction gas includes silane gas, and the purge gas is any one of inert gas, hydrogen gas, nitrogen gas, oxygen gas, and a mixed gas thereof. There is a thin film forming apparatus. In the thin film forming apparatus according to any one of claims 1 to 3, a gas ejection hole penetrating the electrode body is provided at the plurality of positions arranged in the axial direction on the circumferential surface of the electrode body as the gas ejection section. A thin film forming apparatus. 5. The thin film forming apparatus according to claim 4 , wherein the gas ejection holes are provided at a plurality of positions arranged in the circumferential direction on the peripheral surface of the electrode body, and the axial positions of the gas ejection holes are shifted from each other. Thin film forming apparatus. The thin film forming apparatus according to any one of claims 1 to 3 , wherein at least a part of a peripheral wall of the electrode body is formed of a porous body extending in an axial direction of the electrode body as the gas ejection part. Thin film forming apparatus. A rotating electrode having a cylindrical outer peripheral surface, driving means for driving the rotating electrode to rotate, and holding the substrate at a position facing the rotating electrode, the substrate is substantially orthogonal to the rotation center axis with respect to the rotating electrode. And a feed means for moving in the direction of rotation, and generating a plasma between the rotating electrode and the substrate while rotating the rotating electrode, thereby causing a chemical reaction to occur in the reaction gas supplied to the plasma. In a thin film forming apparatus for forming a thin film on the substrate,
As a purge gas layer forming means for forming a gas layer made of a purge gas different from the reaction gas on an outer peripheral surface of the rotating electrode and corresponding to at least a thin film forming region on the substrate, a gap between the rotating electrode and the substrate Alternatively, a purge gas supply means for supplying a purge gas from the upstream side in the rotation direction of the rotating electrode to a position in the vicinity thereof is provided, and the supplied purge gas is entrained in the gap to form a gas layer. A thin film forming apparatus. A plasma is generated between the rotating electrode and the substrate while rotating the rotating electrode having a cylindrical outer peripheral surface, thereby causing a chemical reaction to the reactive gas supplied to the plasma to form a thin film on the substrate. A method of forming,
Forming a gas layer made of a purge gas different from the reaction gas on an outer peripheral surface of the rotating electrode and at least in a region corresponding to a thin film forming region on the substrate;
On the outer peripheral surface of the rotating electrode, a gas ejection portion is provided at least in a region corresponding to the thin film formation region on the substrate, and a gas supply portion communicating with the gas ejection portion is provided at a position different from the gas ejection portion, and the gas layer The step of forming includes the step of supplying the purge gas to the gas supply unit and ejecting the purge gas from the gas ejection part of the rotating electrode onto the electrode peripheral surface,
The electrode body of the rotating electrode is formed in a hollow, substantially cylindrical shape, and a gas ejection portion that communicates the inside and the outside is provided on the peripheral wall of the electrode body, and a gas supply path that communicates the space inside the electrode body with the gas ejection portion,
A cylindrical rotation center shaft is passed through the central portion of the electrode body, a shaft end opening of the rotation center shaft is used as a gas supply portion, and a gas outlet portion is provided on the peripheral wall of the rotation center shaft to communicate the inside and outside. A method for producing a thin film, characterized in that a space between the rotation center axis and the electrode body is a gas stirring chamber. 9. The thin film manufacturing method according to claim 8 , wherein a purge gas supply pipe is inserted into a shaft end opening of a rotation center shaft that is a gas supply portion of the rotary electrode, and purge gas is supplied into the rotation center shaft through the purge gas supply pipe. A method for producing a thin film. 10. The thin film manufacturing method according to claim 8 , wherein the reaction gas includes silane gas, and the purge gas is any one of an inert gas, a hydrogen gas, a nitrogen gas, an oxygen gas, and a mixed gas thereof. A method for producing a thin film, comprising: The thin-film manufacturing method according to any one of claims 8 to 10 , wherein the gas ejection hole is provided with a gas ejection hole penetrating the electrode body at a plurality of positions arranged in the axial direction on the peripheral surface of the electrode body as the gas ejection section. A method for producing a thin film, characterized in that 12. The thin film manufacturing method according to claim 11 , wherein the gas ejection holes are provided at a plurality of positions on the circumferential surface of the electrode main body in a circumferential direction, and rotating electrodes in which the axial positions of the gas ejection holes are shifted from each other are used. A method for producing a thin film. 11. The thin film manufacturing method according to claim 8 , wherein a rotating electrode including at least a part of a peripheral wall of the electrode main body as a porous body extending in an axial direction of the electrode main body is used as the gas ejection portion. A method for producing a thin film. A plasma is generated between the rotating electrode and the substrate while rotating the rotating electrode having a cylindrical outer peripheral surface, thereby causing a chemical reaction to the reactive gas supplied to the plasma to form a thin film on the substrate. A method of forming,
  Forming a gas layer made of a purge gas different from the reaction gas on an outer peripheral surface of the rotating electrode and at least in a region corresponding to a thin film forming region on the substrate;
  In this step, purge gas is supplied from the upstream side in the rotation direction of the rotary electrode to the gap between the rotary electrode and the substrate or in the vicinity thereof, and the gas layer is formed by entraining the supplied purge gas into the gap. A method for producing a thin film. The thin film manufacturing method according to claim 8 , wherein the thin film is amorphous silicon. The thin film manufacturing method according to any one of claims 8 to 14 , wherein the thin film is C. The thin film manufacturing method according to claim 8 , wherein the thin film is SiC. The thin film manufacturing method according to claim 8 , wherein the thin film is SiO 2.

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